Bralorne

Overview

The Bralorne-Pioneer is a past producing gold mine which  has produced in excess of 4 million ounces over a 40 year period.

Placer gold was located at the mouth of the Hurley River near the present town of Gold Bridge in 1882. In 1886, over 1,000 ounces of gold (common nuggets were in the 28 to 142 gram range) were recovered by placer miners from the Cadwallader Creek. In 1897, gold-bearing quartz veins were discovered on the side of the mountain. The mine shut down in 1971 at a time of low gold price.

Bralorne Gold Mines Ltd the present day owner is exploring the historic gold mine property with the aim of establishing mineral resources to justify a new mining operation.

Since acquiring the project from Avino Silver & Gold Mines in 1995, the company has expanded ther holdings, completely re-furbished the facility, obtained all permitting and brought it to operation at 100 tonnes per day.

The company engaged into a thoroughly surface and underground exploration program that expanded several key gold zones and found new ones. In 2004 and 2005 the company collected and processed a 20,000-ton bulk sample that resulted in the recovery of 2,916 ounces of gold.

Bralorne Gold Mines celebrated its grand re-opening on May 27, 2011 when it poured its first gold brick.

Location

 The Bralorne-Pioneer mine is located 112 kilometers west of Lillooet in British Columbia, Canada. The property is approximately 150 air miles from Vancouver. Itcovers an area of approximately 2,422 hectares (5,985 acres).

 The property lies in mountainous terrain with deeply incised stream valleys and moderate to steep slopes. Topographic elevations range from 870 meters on the Hurley River in the northwest part of the property to 1615 meters on the eastern edge of the property. Vegetation on the property consists of mature spruce, pine and interior Douglas-fir. Approximately 40% of the property has been clear cut.

Moderate to heavy snowfall occurs in winter months, with accumulations exceeding three meters on the property. Surface work is generally curtailed during winter months due to these conditions.

Geology & Mineralization

The Bridge River Terrane is possibly equivalent to the Cache Creek Terrane and is comprised of slabs of oceanic and transitional crust that were stacked against the continental margin together with island-arc related units of the Cadwallader Terrane.

The region has been intruded by a wide range of Cretaceous and Tertiary plutonic and volcanic rocks and their hypabyssal equivalents.

The main gold-forming event in the Bridge River district took place at ca. 68 to 64 Ma at the Bralorne-Pioneer deposit. Mineralization pre-dated or was synchronous with the emplacement of the Bendor batholith, and the gold event overlaps initiation of dextral strike-slip on the regional fault systems in this region.

The Bralorne-Pioneer gold-bearing veins were deposited from low salinity fluids at 300 to 400 °C and 1.25 to 1.75 kbar. The vein style, structure, mineralogy, and alteration are all similar to those de fined for orogenic gold deposits.

The Bralone-Pioneer vein system is hosted in the variably altered mafic and ultramafic rocks that occur as fault-bounded lenses in a structurally complex zone between the Bridge River and Cadwallader terranes referred to as the Bralorne Block. The ore bodies occur along an approximate 4.5 km strike length, mostly along, adjacent to, or between the Cadwallader and Fergusson faults. Mineralization was interpreted by Leitch (1990) as synkinematic and structurally controlled by secondary fault sets related to westerly-directed, sinistral transpressional movement along faults bounding the Bralorne ophiolite.

Quartz veins form en echelon arrays, with strike lengths of as much as 1500 m between bounding structures. Veins extend to at least 2000 m in depth, with no significant changes in grade or style of mineralization recorded. Ores consist mainly of ribboned fissure veins with septa defined by fine-grained chlorite, sericite, graphite or sulphide minerals.

Veins are dominantly quartz, with minor carbonate minerals, mainly calcite and ankerite, and lesser amounts of chlorite, sericite, clay altered mariposite, talc, scheelite and native gold. Sulphides are present and, although locally abundant, make up less than 1% of total vein volume. Pyrite and arsenopyrite are the most abundant sulphides with lesser marcassite, pyrrhotite, sphalerite, galena, chalcopyrite and rare tetrahedrite.

A new mineralized zone named BK3 was identified by drilling in the unexplored gaps between the Bralorne, Pioneer and King mines.

Mining & Operations

Bralorne Gold Mines is running an underground exploration program consisting of adits and cross-cuts, to intersect the mineralized structures, and drifts and raises on the vein that enables it to estimate mineral resources. 

Mining and collecting of athe bulk sample is being done by shrinkage stoping.

A 1,400 ft decline is to be built to intersect the 575 level of the new BK3 vein.

Process 

The 500 tonnes per day permitted mill is processing underground ore through crushing, grinding and by employing gravity recovery and flotation methods.

A tailings impoundment with an initial five year capacity has been constructed on the west side of Cadwallader Creek near the mill. There is sufficient waste storage space for many years of mine life if the open stopes below the 800 level are filled or waste is dumped on existing waste piles. 

In 2004 and 2005 the company collected and processed a 20,000-ton bulk sample that resulted in the recovery of 2,916 ounces of gold.

Environment & Community

The mine drainage exceeds the allowable discharge limits for arsenic into Cadwallader Creek, therefore the company is pumping or otherwise divert all the mine discharge water into the tailings impoundment.

Bralorne waste has no potential for acid generation, but silver, arsenic, antimony and selenium, and locally lead and cadmium, are elevated in the mine waste rock. Quarterly monitoring of monitor wells and seep waters is on-going.